Neuroendocrine hyperplasiaUp one level
Groups of uniform small cells with scant cytoplasm and round to oval nuclei with dense speckled chromatin form clusters thickening bronchiolar wall and/or protruding into the lumen. Immunohistochemical staining for markers of neuroendocrine differentiation, such as synaptophysin, CGRP and chromogranin, is required for accurate identification. Not reported to occur spontaneously. Neuroendocrine hyperplasia must be differentiated from normal groups of neuroendocrine cells found more prominently in some mouse strains.